Which term describes the act of being punctiliously exact and painstaking?

The term that best describes the act of being punctiliously exact and painstaking is "meticulously." This word conveys a sense of thoroughness and attention to detail, suggesting that a person is careful about every aspect of their work or actions. When someone is meticulous, they take great care in ensuring that everything is done correctly and with precision, leaving no room for error.

The other terms, while related to care and attention, have slightly different connotations. "Scrupulously" refers to someone who is very concerned about doing the right thing and adhering to moral or ethical standards. "Conscientiously" implies being diligent and having an awareness of one's responsibilities, emphasizing effort and commitment. "Fastidiously" usually indicates a level of delicacy or excessive concern over unimportant details, suggesting a more picky or critical attitude. Therefore, while all these terms express elements of care, "meticulously" most accurately captures the essence of being punctiliously exact and painstaking.